Method and apparatus for cryptographically aligning and binding a secure element with a host device

ABSTRACT

A method of cryptographically binding a secure element to a host device includes storing host key information in a host key information slot of the secure element and storing binding information in secure memory of the secure element. The binding information is correlated with the host key information. The method includes storing a second secret key within system operational code of the host device. The second secret key is cryptographically correlated with the host key information. The method includes, after storing the binding information and after storing the second secret key, operationally coupling the secure element to the host device, reading, by the host device, the binding information from the secure element, generating, by the host device, the host key information using the binding information and the second secret key, and storing, by the host device, the host key information in a host key information slot of the host device.

TECHNICAL FIELD

The present invention relates generally to cryptographic alignment, and, in particular embodiments, to methods and apparatuses for cryptographically aligning a secure element with a host device.

BACKGROUND

Device security is important to protect the contents of data as well as guarantee the identity of devices generating the data. A secure element can be used to store and apply sensitive data such as cryptographic keys and securely execute computer code such as electronic payment applications for a host device, or cryptographically support transport layer security (TLS) for internet of things (IoT) devices. The secure element includes active and/or passive prevention measures render it infeasible for unauthorized entities to read the contents in memory of the secure element or discover crypto secrets stored in the secure element. The secure element is cryptographically bound to the host device using host key information known only to the secure element and the host device.

Among other uses, the secure element can be used as the basis of the identity of the host device. In order to guarantee the identity of the host device, it is important that the host key information is not discovered by an external entity. The host key information may be stored in the secure element and then subsequently sent to the host device during a binding process. However, the secure element and the host device may be manufactured at separate locations and/or by different manufacturers. As a result, the binding process may be performed at an insecure location. For example, the host key information may be vulnerable to discovery during the binding process when the host key information is transmitted from the secure element to the host device, or when the host device sends the command to personalize the secure element with the host keys. Therefore, binding processes between a secure element and a host device which reduce or eliminate the possibility of an external entity discovering host key information may be desirable.

SUMMARY

In accordance with an embodiment of the invention, a method of cryptographically binding a secure element to a host device includes storing host key information in a secure element host key information slot of the secure element and storing binding information in secure memory of the secure element at a first location. The binding information is cryptographically correlated with the host key information. The method also includes storing a second secret key within system operational code stored in protected memory of the host device at a second location remote to the first location. The second secret key is cryptographically correlated with the host key information. The method further includes, at a third location after storing the binding information and after storing the second secret key SK₂, operationally coupling the secure element to the host device, reading, by the host device, the binding information from the secure element, generating, by the host device, the host key information using the binding information and the second secret key, and storing, by the host device, the host key information in a host device host key information slot of the host device. The secure element and the host device are collocated at the third location. The third location is remote to both the first location and the second location.

In accordance with another embodiment, a method of cryptographically aligning a secure element with a host device includes generating a secure element-diversified key as a function of a master key and a secure element unique identifier and encrypting host key information using the secure element-diversified key to generate encrypted host key information. The host key information HK_(SE) uniquely corresponds to the secure element. The method also includes storing the host key information in a secure element host key information slot of the secure element, storing the encrypted host key information in secure memory of the secure element, and obfuscating the master key using a host device unique identifier to generate a host device-obfuscated key within system operational code stored in protected memory of the host device.

In accordance with still another embodiment of the invention, a method of cryptographically binding a secure element to a host device includes storing a secure element private key in secure memory of the secure element, creating a secure element public key using the secure element private key, storing a host device private key within system operational code stored in protected memory of the host device, and operationally coupling the secure element and the host device. The method further includes executing the system operational code by the host device. Executing the system operational code includes reading the secure element public key from the secure element, creating host key information using the host device private key and the secure element public key, and storing the host key information in a host device host key information slot of the host device.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:

FIG. 1 illustrates a method of cryptographically aligning a secure element with a host device in accordance with an embodiment of the invention;

FIG. 2 illustrates a method of cryptographically binding a secure element to a host device in accordance with an embodiment of the invention;

FIG. 3 illustrates a method of securely acquiring proprietary information by a host device cryptographically bound to a secure element in accordance with an embodiment of the invention;

FIG. 4 illustrates schematic block diagrams of a secure element, host device, and hardware security modules usable for cryptographic alignment, binding, and secure acquisition of proprietary information in accordance with an embodiment of the invention;

FIG. 5 illustrates a method of cryptographically aligning a secure element with a host device using a master key and encrypted host key information in accordance with an embodiment of the invention;

FIG. 6 illustrates a method of cryptographically binding a secure element to a host device using a master key and encrypted host key information in accordance with an embodiment of the invention;

FIG. 7 illustrates schematic block diagrams of a secure element, host device, and hardware security modules usable for cryptographic alignment, binding, and secure acquisition of proprietary information using a master key and encrypted host key information in accordance with an embodiment of the invention;

FIG. 8 illustrates a method of cryptographically aligning a secure element with a host device using a secure element public key and a host device private key in accordance with an embodiment of the invention;

FIG. 9 illustrates a method of cryptographically binding a secure element to a host device using a secure element public key and a host device private key in accordance with an embodiment of the invention; and

FIG. 10 illustrates schematic block diagrams of a secure element, host device, and hardware security modules usable for cryptographic alignment, binding, and secure acquisition of proprietary information using a secure element public key and a host device private key in accordance with an embodiment of the invention.

Corresponding numerals and symbols in the different figures generally refer to corresponding parts unless otherwise indicated. The figures are drawn to clearly illustrate the relevant aspects of the embodiments and are not necessarily drawn to scale. The edges of features drawn in the figures do not necessarily indicate the termination of the extent of the feature.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The making and using of various embodiments are discussed in detail below. It should be appreciated, however, that the various embodiments described herein are applicable in a wide variety of specific contexts. The specific embodiments discussed are merely illustrative of specific ways to make and use various embodiments, and should not be construed in a limited scope.

Secure elements include security features which enable secure storage of sensitive data as well as secure processing within the secure element for a paired host device. A secure element can be a microcontroller (MCU) or a microprocessor (MPU) that includes security features. A specific example of a secure element is the STSAFE family of secure microcontrollers including the STSAFE-A100, for example. A host device may be a computing device such as an MCU or an MPU. A specific example of a host device is the STM32 family of microcontrollers.

A host device may be considered paired with a secure element when the host device is cryptographically bound to the secure element using host key information known only to the secure element and the host device. The host device may have reduced security capabilities or no security capabilities. That is, a host device in the context of the present disclosure may be any device that can be cryptographically bound to a secure element in order to derive benefit from the additional security features afforded by the secure element.

Host key information may include one or more cryptographic keys. In various embodiments, the host key information includes one or more symmetric keys. For example, the host key information may include a private key created at a secure fabrication location. The host key information may include a message authentication code (MAC) key so that the secure element can verify that a received command is sent from the host device and vice versa. The host key information may also include an encryption key that can be used by the secure element and the host device to encrypt and decrypt information that is transferred between the secure element and the host device (e.g. on an electrical bus).

Although the above examples utilize symmetric keys, the host key information is not limited to symmetric encryption schemes. For example, a public key (e.g. a certificate) may be created using a signed key that is also secure. For example, the private key and public key may be created and certified using a hardware security module (HSM). The host key information may enable secure communication between the host device and the secure element.

Prior to the pairing of the secure element and the host device, security critical functionality of the secure element is unavailable to the host device. That is, it is not possible for the host device to send certain commands to the secure element and for the secure element to execute the command without the host device having the host key information. Therefore, data stored on the secure element which solution users may want to protect cannot be read and interpreted for any reason by the host device without the host key information. Once the host device is operatively coupled to the secure element, the pairing process begins or is initiated using a predetermined process and runs to completion resulting in the host key information being securely stored on the host device. Once the secure element and the host device are cryptographically bound, the host device is able to send commands to the secure element to obtain data stored on the secure element in addition to other secure functionality.

Secure elements may be used as the basis of identity for host devices such as IoT devices. For example, with the ubiquity of connected devices, IoT devices may be used in applications requiring credentials or in operating valuable services (e.g. devices that are susceptible to fraud or counterfeiting, USB Type-C devices, accessories for electronic devices such as phones or gaming devices, consumables such as printer cartridges, and the like). IoT devices can also include thermostats, doorbell cameras, and security devices which may be enabled with customer Wi-Fi credentials and could be used to compromise end customer security should a device be compromised during or after the device's manufacture. Using a secure element, it is infeasible to discover and create a clone of authentication information such as a private key.

The infeasibility of compromising the private key of the host device may advantageously guarantee the identity of the host device. In many applications the guaranteeing the identity of the host device may be important such as when the host device has control over critical systems and/or access to sensitive information. Secure elements may also provide security for other types of host devices such as servers, personal computers, laptop computers, tablet computers, cellular phones, routers, switches, base stations, access points, data concentrators, gateways, medical devices, automotive equipment, and others.

Since secure elements fill a specific role of providing security for a host device, it may be possible for all secure elements to be manufactured at secure locations with access to an HSM to provide a certificate basis for host key information. However, it may be difficult or impossible to provide host devices with the same security during fabrication due to the many different applications of the host devices and various fabrication locations. For example, billions of general purpose microcontrollers may be shipped in a year from multiple fabrication facilities to numerous costumers destined for various applications and chipset environments. Some of the general purpose microcontrollers may become host devices paired with a secure element while others may not require any additional security. Further, a secure element may be paired with a host device that is not manufactured by the same manufacturer as the secure element. Consequently, using conventional methods, there may be no easy way to initialize host key information with a certificate basis for each host device for specific customers for end-customer use.

In order to maintain effectiveness of the secure element, host devices that use a secure element should be paired with the secure element in such a way as to only allow the host device to control the secure element. This may be achieved by using host key information known only to the secure element and the host device. For example, the host key information may be installed in secure memory locations in both the secure element and the host device. However, when the secure element and the host device are brought together to be cryptographically bound, it is not uncommon for only the secure element to have the host key information and for the manufacturing location to lack the security required to guarantee the secrecy of the host key information. That is, the manufacturing location may not be trusted and the host key information may be compromised while being transferred from the secure element to the host device.

During conventional pairing processes, a secure element may send a random number to chipset initialization equipment which gets installed in an appropriate location in the host device so as to function as host key information, and commands the secure element to be the host key (one time process). However, in these conventional pairing processes, secrecy of the random number is only guaranteed if the chipset manufacturing location is secure since the random number is sent in the clear between the secure element and the host device. Therefore, a pairing process to cryptographically bind a secure element to a host device that does not send the raw host key information from the secure element to the host device may be desirable.

Various embodiments described herein provide methods and apparatuses that cryptographically align a secure element with a host device prior to a cryptographic binding process. The disclosed embodiments store binding information in the secure element and store a secret key in the host device. The binding information is cryptographically correlated with the secret key. During the binding process, host key information can be generated by the host device using the binding information and the secret key. Through these techniques, the disclosed embodiments may provide various advantages including secrecy of host key information during a binding process between a secure element and a host device. Additional implementations and advantages may be apparent to one of ordinary skill in the art in view of the following description.

In particular, there is a cryptographic correlation between information stored in the secure element and information stored the host device during initialization in trusted manufacturing facilities so that subsequently the secure element and the host device may advantageously be securely paired in a potentially insecure environment. Further, the cryptographic alignment of the secure element and the host device prior to being brought together beneficially obscures the binding process using encryption so that it is infeasible or impossible for a contract manufacturer or parties on the manufacturer's line to observe the host key information during the binding process because the host key information itself is not transmitted in the clear between the secure element and the host device. Another possible advantage is that no HSM is needed at the chipset manufacturing location. For example, an HSM may not be necessary on the manufacturing line of a customer or the manufacturing line of a subcontractor of a customer when cryptographically binding a secure element and a host device which may beneficially reduce costs. Further, once a secure element and a host device are securely bound using the processes herein, additional keys stored in the secure element may be used advantageously as the secure basis to personalize the host device without the need for an HSM. For example, the secure element may be used as a hardware license to allow only the host device or limited number of host devices to access additional proprietary information.

Embodiments provided below describe various methods and apparatuses for cryptographically aligning a secure element with a host device, and in particular, methods and apparatuses that store binding information in a secure element and storing a secret key in the host device, the binding information being cryptographically correlated to the secret key. The following description describes the embodiments. An embodiment method of cryptographically aligning a secure element with a host device is described using FIG. 1. An embodiment method of cryptographically binding a secure element to a host device is described using FIG. 2. An embodiment method of securely acquiring proprietary information by a host device cryptographically bound to a secure element is described using FIG. 3. Embodiment schematic block diagrams of a secure element, host device, and hardware security modules usable for cryptographic alignment, binding, and secure acquisition of proprietary information are described using FIG. 4. Two more embodiment methods of cryptographically aligning a secure element with a host device are described using FIGS. 5 and 8. FIGS. 6 and 9 are used to describe another two embodiment methods of cryptographically binding a secure element to a host device. Additional embodiment schematic block diagrams secure elements, host devices, and hardware security modules usable for cryptographic alignment, binding, and secure acquisition of proprietary information are described using FIGS. 7 and 10.

The method steps described herein may be performed in any suitable order as may be apparent to those of skill in the art. Additionally, any suitable combination of steps in the methods described herein may be performed concurrently as may be apparent to those of skill in the art. Except where explicitly indicated, embodiment methods are not intended to be limited to the specific order of the method steps as shown and described which may be chosen for reasons of clarity and brevity.

FIG. 1 illustrates a method of cryptographically aligning a secure element with a host device in accordance with an embodiment of the invention.

Referring to FIG. 1, a cryptographic alignment method 100 includes an initial state 10 in which a secure element and a host device are uncorrelated. For example, the secure element and the host device may not be initialized in the initial state 10. The secure element and/or the host device may or may not include stored executable code or data unrelated to the alignment process at the initial state 10. Specifically, no information that links the secure element to the host device is stored on either the secure element or the host device in the initial state 10.

After the initial state 10 during which the secure element and the host device are uncorrelated, step 104 includes storing binding information B_(SE) in secure memory of the secure element. The binding information B_(SE) is cryptographically correlated to the host key information HK_(SE) and may be used in combination with other information to generate host key information HK_(SE). Optionally, the host key information HK_(SE) may be stored in a host key information slot SE-HK_(SE) of the secure element in step 102 of cryptographic alignment method 100. The binding information B_(SE) may also be cryptographically correlated with (e.g. generated from or otherwise based on) a first secret key SK₁ which may optionally be stored in the secure memory of the secure element in step 105. In some embodiments, the first secret key SK₁ may be used in combination with the binding information B_(SE) to generate the host key information HK_(SE).

In step 107, a second secret key SK₂ is stored within system operational code stored in protected memory of the host device. The second secret key SK₂ is cryptographically correlated with the host key information HK_(SE). The second secret key SK₂ can be used in combination with the binding information B_(SE) to generate the host key information HK_(SE). Once the binding information B_(SE) is stored in the secure element in step 104 and the second secret key SK₂ is stored in the host device in step 107, the secure element and the host device are cryptographically aligned as shown in aligned state 120. In other words, in the aligned state 120, both the secure element and the host device have information stored thereon that may be used to generate the host key information.

The steps involving the secure element (i.e. step 104 and optional steps 102 and 105) may be performed at a manufacturing location of the secure element. For example, any of the steps 102, 104, and 105 may be performed on a personalization line at a secure location. Similarly, step 107 (which involves the host device) may be performed at a manufacturing location of the host device, such as a personalization line of the host device. The host device manufacturing location may or may not be secure. The secure element manufacturing location and the host device manufacturing location may be geographically separate locations. Put another way, the secure element manufacturing location may be remote to the host device manufacturing location.

Since both the binding information B_(SE) and the second secret key SK₂ are correlated with the host key information HK_(SE) it may be necessary to securely transport secret information from the secure element manufacturing location to the host device manufacturing location in an optional step 106. Alternatively, the secret information may be securely transported from the host device manufacturing location to the secure element manufacturing location. In some embodiments, the secret information may be used for more than one alignment process rendering it unnecessary to repeatedly transport the information between locations. In other embodiments, no secret information is transported between the secure element manufacturing location and the host device manufacturing location because the host key information HK_(SE) is not generated at either location.

FIG. 2 illustrates a method of cryptographically binding a secure element to a host device in accordance with an embodiment of the invention.

Referring to FIG. 2, a cryptographic binding method 200 includes an initial state which is an aligned state 120 in which a secure element and a host device are cryptographically aligned. The alignment may be performed in accordance with cryptographic alignment methods as describe herein, such as the cryptographic alignment method 100 of FIG. 1, for example. The alignment process may be geographically separated from a binding location where the cryptographic binding method 200 is performed and at which the secure element and the host device are collocated. For example, the binding location may be at a manufacturer of a device using both ICs that is remote to locations such as a secure element manufacturing location and a host device manufacturing location.

After the aligned state 120, the secure element is operationally coupled to the host device in step 210. In one embodiment, operationally coupling the secure element to the host device includes connecting the secure element to the host device using an electrical bus over which commands and data can be sent. Alternatively, the secure element and the host device may be directly connected or packaged together, such as in a system-on-a-chip configuration, for example.

All general functionality of the secure element may be disabled at the moment of operational coupling to the host device. The secure element is configured to operate in a predetermined limited capacity during the binding process in order to establish a paired (i.e. cryptographically bound) relationship with a host device. After step 210 of operationally coupling the secure element to the host device, the binding process may optionally be initiated by sending a predetermined command to the host device in step 211. The initiate command may trigger boot-up of system operational code stored in protected memory of the host device. Alternatively, the binding process may be triggered without an initiate command, such as automatically when the host device and the secure element receive power.

At the beginning of the binding process, the secure element may be locked. For example, the secure element may optionally be unlocked by a password in step 212. In one embodiment, the password is a batch password that can be used for multiple binding processes and which is changed periodically to avoid security issues. The batch password may be known at the location of the binding process, but may be transported to the location separately from both the secure element and the host device. In this way, an unauthorized party would be unable to initiate the binding process by merely intercepting the secure element and the host device. When an initiate command is used to begin the binding process, the initiate command may include the password so that the system operational code of the host device uses the password to unlock the secure element to continue the binding process.

After step 210, the host device reads the binding information B_(SE) from the secure element in step 215. The binding information B_(SE) may be transmitted between the secure element and the host device over an insecure data link such as an electrical bus. However, the host key information HK_(SE) is advantageously not compromised in the event of the binding information B_(SE) being intercepted by a nefarious party because additional information is needed with the binding information B_(SE) in order to generate the host key information HK_(SE).

Once the host device has read the binding information B_(SE) from the secure element, the host device generates the host key information HK_(SE) using the binding information B_(SE) and the second secret key SK₂ stored in the host device in step 217. More information may also be used in addition to the binding information B_(SE) and the second secret key SK₂ to generate the host key information HK_(SE). For example, the password used to unlock the secure element may also be used by the host device in conjunction with the binding information B_(SE) and the second secret key SK₂ to generate the host key information HK_(SE) in some embodiments. In various embodiments, the host device may generate the first secret key SK₁ from the second secret key SK₂ and generate the host key information HK_(SE) using the binding information B_(SE) and the first secret key SK₁.

In step 218, once the host device has generated the host key information HK_(SE), the host device stores the host key information HK_(SE) in a host key information slot HD-HK_(SE) of the host device. The secure element is cryptographically bound to the host device in bound state 30 once the host key information HK_(SE) is stored in both the secure element and the host device. The secure element may optionally generate the host key information using the first secret key SK₁ in step 213 and store the host key information HK_(SE) in a host key information slot SE-HK_(SE) of the secure element in step 214. Alternatively, the host key information HK_(SE) may have been generated and stored in the secure element prior to the cryptographic binding method 200.

After the host key information HK_(SE) is generated by the host device in step 217, the second secret key SK₂ may optionally be deleted from the host device in step 219. For example, the second secret key SK₂ may be deleted from both volatile memory (e.g. random-access memory) and nonvolatile memory (e.g. program memory). Additional information related to the generation of the host key information HK_(SE) may also be deleted from the host device such as the binding information B_(SE) and the batch password.

In the event that there is a problem during the binding process in which the host key information is improperly installed in the host device, it may be impossible or infeasible to recover the host device. The binding process may be conducted in protected memory of the host device which may include various safeguards. For example, the capability to enter a debug mode may be turned off or fused following the binding process. Therefore, if there is a problem during the binding process such that, after the binding process, the host device is not successfully bound to the secure element, the host device is effectively unusable. In one embodiment, a secure-backup-data file may be stored on the secure element that may be retrieved by an out-of-band process in the event that the host key information that is installed on a host device is not uncorrupted. The secure-backup-data file may be an encrypted object that can be used to resurrect host devices that have encountered a problem during the binding process.

FIG. 3 illustrates a method of securely acquiring proprietary information by a host device cryptographically bound to a secure element in accordance with an embodiment of the invention.

Referring to FIG. 3, a method of securely acquiring proprietary information 300 includes a bound state 30 in which a secure element and a host device are cryptographically bound. The binding may be performed in accordance with cryptographic binding methods as described herein, such as the cryptographic binding method 200 of FIG. 2, for example.

Prior to the bound state 30, a proprietary information key K_(PI) is wrapped in step 321 to form a proprietary information key WK_(PI). The proprietary information key K_(PI) may be an encryption key. For example, the proprietary information key K_(PI) may be an AES key. In one embodiment, the proprietary information key K_(PI) is a 256 bit AES key. There may be any suitable number of proprietary information keys which correspond with any suitable number of encrypted blocks of proprietary information.

The proprietary information key K_(PI) may be wrapped by the secure element at a secure element manufacturing location during initialization of the secure element. In some embodiments, the proprietary information key K_(PI) may be wrapped using a local enveloped key known only to the secure element. In other words, only the secure element can recover the proprietary information key K_(PI).

The wrapped proprietary information key WK_(PI) is then stored in secure memory of the secure element in step 322. The secure memory may be partitioned (or zoned) to further improve security of the stored data. Additional wrapped proprietary information keys may also be stored in the secure memory of the secure element. The wrapped proprietary information key WK_(PI) may be stored in the secure element at the secure element manufacturing location. Alternatively, the wrapped proprietary information key WK_(PI) may be stored in the secure element at a different location prior to being bound to the host device.

At some time after the wrapped proprietary information key WK_(PI) is stored in the secure element and once the secure element and the host device are in the bound state 30, the host device reads the wrapped proprietary information key WK_(PI) from the secure element in step 331. The host device then instructs the secure element to unwrap the wrapped proprietary information key WK_(PI) and provide the host device with the proprietary information key K_(PI) in step 332.

Since the secure element and the host device are cryptographically bound, the host device uses the host key information HK_(SE) to communicate with the secure element in steps 331 and 332. For example, the read command in step 331 may be authenticated by the secure element using a MAC key that is part of the host key information HK_(SE). Similarly, when the secure element provides the proprietary information key K_(PI) to the host device, the secure element may encrypt the proprietary information key K_(PI) using an encryption key that is part of the host key information HK_(SE) before sending it to the host device. The host device can read the proprietary information key K_(PI) because the host device also has the host key information HK_(SE). In contrast, an unauthorized party advantageously cannot read the proprietary information key K_(PI) in the event that it is intercepted between the secure element and the host device because the host key information HK_(SE) is known only to the secure element and the host device.

At some time before step 334, encrypted proprietary information is loaded into the host device in step 341. For example, the encrypted proprietary information may be loaded into the host device during initialization at a host device manufacturing location. Alternatively, the encrypted proprietary information may be loaded into the host device at the binding location by chipset initialization equipment. However, the encrypted proprietary information may be loaded into the host device at any time prior to step 334. For example, the encrypted proprietary information may be loaded into the host device after step 332 in some embodiments.

At step 334, the host device has both the encrypted proprietary information and the proprietary information key K_(PI). The host device decrypts the encrypted proprietary information using the proprietary information key K_(PI) to obtain the proprietary information. The proprietary information may be any type of restricted information. In various embodiments, the proprietary information is proprietary executable computer code. In one embodiment, the proprietary information is firmware and the method of securely acquiring proprietary information 300 is part of a secure firmware installation (SFI). In other embodiments, the proprietary information is software that is installed on the host device. For example, a database at the binding location may store multiple blocks of encrypted proprietary information. The encrypted proprietary information cannot be used at the binding location without corresponding proprietary information keys. In this way, the secure element can advantageously be used as a hardware license to authorize a host device to install proprietary information such as firmware at the binding location without compromising the security of the proprietary information.

As an alternative to the host device decrypting the encrypted proprietary information directly, the secure element may instead directly decrypt encrypted blocks of proprietary information sent by the host device. For example, the secure element may use a pre-stored, shared key for the purpose of decrypting the proprietary information. The shared key may be stored in a key table. After the secure element and the host device are paired, the host device may command the secure element to decrypt blocks of encrypted proprietary information during an installation process (e.g. a secure firmware installation). This may provide an additional advantage of the shared key only being used by the secure element rather than the host device and the secure element. In other embodiments, the secure element may use the shared key to decrypt a firmware encryption key that is sent to the secure element (e.g. in a first stage bootloader) at the time of the firmware installation. In addition, shared keys that are pre-stored in a key table of the secure element may also be used by the secure element for other purposes (e.g. to decrypt other keys corresponding to other proprietary information).

In some embodiments, the secure element may be used to validate installation of multiple blocks of proprietary information. A counter may be included in the secure element that is decremented each time a proprietary information key is used. The secure element may disallow a host device to obtain access to proprietary information once the counter is equal to zero. Alternatively, multiple counters may be included in the secure element which may be decremented on a per key basis each time a specific proprietary information key is used. The secure element can then provide a further advantage of enforcing bulk license agreements for proprietary firmware and/or software.

FIG. 4 illustrates schematic block diagrams of a secure element, host device, and hardware security modules usable for cryptographic alignment, binding, and secure acquisition of proprietary information in accordance with an embodiment of the invention. The schematic block diagrams of FIG. 4 may schematically illustrate implementations of one or more of the methods described herein, such as the cryptographic alignment method 100, the cryptographic binding method 200, and the method of acquiring proprietary information 300 of FIGS. 1, 2, and 3 respectively, as examples.

Referring to FIG. 4, a secure element 450 (SE 450) and optionally a secure element hardware security module 470 (HSM_(SE) 470) are located at a secure element manufacturing location 95. The secure element manufacturing location 95 may be a secure (e.g. trusted) facility. In various embodiments, the secure element manufacturing location 95 includes equipment such as the HSM_(SE) 470 which can securely generate and certify cryptographic information for devices such as the secure element 450. For example, the HSM_(SE) 470 may generate one or more of host key information HK_(SE), binding information B_(SE), a first secret key SK₁, and a proprietary information key K_(PI).

It should be noted that the secure element manufacturing location 95 may also be the fabrication location for the secure element 450, but this is not a requirement. For example, the secure element 450 may be fabricated at a different location and shipped in an uninitialized state to the secure element manufacturing location 95 where it is initialized on a secure element personalization line.

The secure element 450 includes a secure element host key information slot 56 (SE-HK_(SE) slot 56) configured to securely store the host key information HK_(SE). For example, one or more memory storage locations of fixed size corresponding to the key size of one or more host keys may be included in the SE-HK_(SE) slot 56. The SE-HK_(SE) slot 56 may be part of the firmware of the secure element 450. In one embodiment, the SE-HK_(SE) slot 56 includes a 128 bit slot. Alternatively or additionally, the SE-HK_(SE) slot 56 includes a 192 bit slot, a 196 bit slot, a 256 bit slot, or any other suitable slot size according to the desired strength of security. The secure element 450 may also include any suitable number of additional key slots such as a local envelope slot, a public key slot, one or more private key slots (e.g. a private key table), and the like.

The host key(s) included in the host key information HK_(SE) may conform to an encryption scheme. In one embodiment, the host key information HK_(SE) includes advanced encryption standard (AES) key(s). However, the host key information HK_(SE) may also include triple data encryption standard (3DES), Twofish, and Blowfish keys, among others. It should also be noted that although the preceding encryption schemes describe symmetric encryption schemes, asymmetric encryption schemes may also be applied to keys or generate keys included in the host key information HK_(SE). For example the host key information HK_(SE) may include or be generated by elliptic-curve cryptography (ECC), elliptic-curve Diffie-Hellman (ECDH), the Rivest-Shamir-Adleman (RSA) algorithm, and others.

The host key information HK_(SE) may optionally be stored in the SE-HK_(SE) slot 56 of the secure element 450 at the secure element manufacturing location 95 in a step 402. The host key information HK_(SE) may optionally be generated using the first secret key SK₁ in step 413 and optionally stored in secure memory 52 of the secure element 450 in step 405. Binding information B_(SE) is stored in the secure memory 52 of the secure element 450 in step 404. The binding information B_(SE) may optionally be generated using the first secret key SK₁ in step 403.

The proprietary information key K_(PI) is wrapped to form a wrapped proprietary information key WK_(PI) in step 421. The wrapped proprietary information key WK_(PI) is stored in the secure memory 52 of the secure element 450 in step 422. For example, the HSM_(SE) 470 may provide the proprietary information key K_(PI) instruct the secure element 450 to wrap the proprietary information key K_(PI) to form the wrapped proprietary information key WK_(PI) and store the wrapped proprietary information key WK_(PI) in the secure memory 52. The secure element 450 may use a local envelop key known only to the secure element 450 to wrap the proprietary information key K_(PI). In this way, only the secure element 450 is capable of recovering the proprietary information key K_(PI) from the wrapped proprietary information key WK_(PI).

Still referring to FIG. 4, a host device 460 (HD 460) and optionally a host device hardware security module 480 (HSM_(HD) 480) are located at a host device manufacturing location 96. In various embodiments, the host device manufacturing location 96 is geographically separate from (i.e. remote to) the secure element manufacturing location 95. The host device manufacturing location 96 may be a secure (e.g. trusted) facility. The security level of the host device manufacturing location 96 may be equal to or less than the security level of the secure element manufacturing location 95. For example, as illustrated in FIG. 4, both the secure element manufacturing location 95 and the host device manufacturing location 96 may include an HSM to securely generate and certify cryptographic information. However, in various embodiments, the HSM_(HD) 480 may not issue certificates and instead rely on information that is securely transported to the host device manufacturing location 96 from the secure element manufacturing location 95.

The host device 460 includes a host device host key information slot 66 (HD-HK_(SE) slot 66) configured to securely store the host key information HK_(SE) after the binding process. Although the HD-HK_(SE) slot 66 is not required to be similar to the SE-HK_(SE) slot 56, the HD-HK_(SE) slot 66 is substantially similar to the SE-HK_(SE) slot 56 in several embodiments. That is, the memory size of the HD-HK_(SE) slot 66 is substantially similar to the memory size of the SE-HK_(SE) slot 56 in several embodiments. The HD-HK_(SE) slot 66 may be part of the firmware of the host device 460.

A second secret key SK₂ is generated and stored in system operational code 464 (SOC 464) of the host device 460 in step 407. For example, the HSM_(HD) 480 may generate the second secret key SK₂. The system operational code 464 may function as a secure bootloader for the host device. The system operational code 464 is stored in protected memory 62 of the host device 460. That is, the protected memory 62 may be memory that is protected from readout. Protected memory 62 may include nonvolatile memory (NVM) such as flash memory that cannot be read by an external device. Protected memory 62 may also include read-only memory (ROM) that cannot be modified by programming instructions. Some or all of the system operational code 464 may be stored in ROM. Protected memory 62 may also include random-access memory (RAM). Within the scope of this disclosure, data stored in protected memory 62 is considered to be protected from unauthorized access at least while performing the methods described herein and is intended to include all forms of memory suitable for such a purpose. Further, the protected memory 62 may be implemented in any suitable manner such as attack resistant technology (e.g. TrustZone® in an advanced reduced instruction set computing (RISC) machine (ARM) processor), or using any suitable means of making the protected memory 62 secure against software or hardware attacks may be utilized.

Since the binding information B_(SE) at the secure element manufacturing location 95 and the second secret key SK₂ at the host device manufacturing location 96 are both cryptographically correlated to the host key information HK_(SE) used as a basis to cryptographically bind the secure element 450 and the host device 460, secret information may optionally be securely transported from the secure element manufacturing location 95 to the host device manufacturing location 96 in step 406. Secret information may also be securely transported from the host device manufacturing location 96 to the secure element manufacturing location 95.

The second secret key SK₂ may be generated at the host device manufacturing location 96 using the secret information from the secure element manufacturing location 95. In some embodiments, the secret information may also be used to generate the first secret key SK₁ at the secure element manufacturing location 95. For example, the secret information may be another secret key known at both the locations and securely stored in both the HSM_(SE) 470 and the HSM_(HD) 480. Alternatively, the first secret key SK₁ and the second secret key SK₂ may be the same key. In other embodiments, the first secret key SK₁ and the second secret key SK₂ may be independent of one another.

Encrypted proprietary information CPI may optionally be stored in protected memory 62 in step 441. Alternatively, the encrypted proprietary information CPI may be provided to the host device 460 at a different location (e.g. during or after the binding process). The encrypted proprietary information CPI may be decrypted using the proprietary information key K_(PI) to generate proprietary information PI. Since the encrypted proprietary information CPI is protected by encryption, the encrypted proprietary information CPI may also be stored in unprotected NVM of the host device in some embodiments.

The secure element 450 may be cryptographically bound to the host device 460 at a chipset manufacturing location 97 which may be geographically separate from (i.e. remote to) both the secure element manufacturing location 95 and the host device manufacturing location 96. The secure element 450 is transported from the secure element manufacturing location 95 to the chipset manufacturing location 97 in step 408. Similarly, the host device 460 is transported from the host device manufacturing location 96 to the chipset manufacturing location 97 in step 409. At this point, the secure element 450 and the host device 460 are collocated at the chipset manufacturing location 97. That is, the secure element 450 and the host device 460 are physically in the same location.

The secure element 450 is operatively coupled to the host device 460 in step 410. For example, an electrical bus such as a data bus 92 may couple the secure element 450 to the host device 460. Chipset initialization equipment may also be included to initiate the pairing process. Chipset initialization equipment may also optionally provide the encrypted proprietary information CPI in step 441 at the chipset manufacturing location 97 if the encrypted proprietary information CPI was not provided earlier.

The host device 460 reads the binding information B_(SE) from the secure element 450 in step 415. The binding information B_(SE) travels on the data bus 92, but does not jeopardize the security of the host key information HK_(SE) because the host key information HK_(SE) cannot be generated solely from the binding information B_(SE). The host device 460 generates the host key information HK_(SE) using the binding information B_(SE) and the second secret key SK₂ in step 417 and stores the host key information HK_(SE) in the HD-HK_(SE) slot 66 of the host device 460 in step 418. After the host key information HK_(SE) has been installed in the HD-HK_(SE) slot 66 of the host device 460, the second secret key SK₂ is optionally deleted in step 419 to further protect the anonymity of the host key information HK_(SE). For example the binding process stored in the system operational code 464 may be atomic and delete all key material as soon as it is used.

After the host key information HK_(SE) is stored in both the SE-HK_(SE) slot 56 and the HD-HK_(SE) slot 66, the secure element 450 and the host device 460 are cryptographically bound. Optionally, if the host key information HK_(SE) was not stored in the SE-HK_(SE) slot 56 at the secure element manufacturing location 95, the host key information HK_(SE) may be generated by the secure element 450 using the first secret key SK₁ together with additional information in step 413 and stored in the SE-HK_(SE) slot 56 in step 414. The additional information may be provided by the host device 460, for example.

After the secure element 450 and the host device 460 are cryptographically bound, the host device 460 uses the host key information HK_(SE) stored in the HD-HK_(SE) slot 66 to read the wrapped proprietary information key WK_(PI) from the secure element 450 in step 431 and instruct the secure element 450 to unwrap the wrapped proprietary information key WK_(PI) to generate the proprietary information key K_(PI) in step 432. The proprietary information key K_(PI) is then provided to the host device 460 in step 433. In step 434, the host device 460 uses the proprietary information key K_(PI) to decrypt the encrypted proprietary information CPI and generate the proprietary information PI. Advantageously, since the secure element 450 and host device 460 are paired using the host key information HK_(SE) which has not been compromised, the proprietary information key K_(PI) is encrypted using the host key information HK_(SE) by the secure element 450 after being unwrapped and is not exposed during transport on data bus 92.

FIG. 5 illustrates a method of cryptographically aligning a secure element with a host device using a master key and encrypted host key information in accordance with an embodiment of the invention. The method of FIG. 5 may be a specific implementation of other methods described herein, such as the cryptographic alignment method 100 of FIG. 1, for example. Similarly labeled elements may be as previously described.

Referring to FIG. 5, a cryptographic alignment method 500 includes the initial state 10 which may be as previously described. A secure element-diversified key K_(SE) is generated as a function of a master key K_(M) and a secure element unique identifier UID_(SE) in step 501. In various embodiments the secure element-diversified key K_(SE) is an AES key and is a 128 bit AES key in one embodiment. Similarly, the master key K_(M) is an AES key in some embodiments and is a 128 bit AES key in one embodiment.

The master key K_(M) is secret information. The master key K_(M) may only be internally known by hardware security equipment, for example. The secure element unique identifier UID_(SE) uniquely identifies the secure element. Advantageously, the secure element-diversified key K_(SE) is a cryptographic secret due to the dependence on the master key K_(M). Additionally, the secure element-diversified key K_(SE) is unique to the secure element because of the dependence on the secure element unique identifier UID_(SE). In some embodiments, the secure element-diversified key K_(SE) may be generated without using a unique identifier.

Optionally, the secure element-diversified key K_(SE) may also be generated in step 501 as a function of the master key K_(M), the secure element unique identifier UID_(SE), and a password. For example, the password may be a batch password that is the same for a batch of secure elements, but that is changed periodically. In contrast, the master key K_(M) may not be changed or may only be changed if there is reason to believe it has been compromised (i.e. a static or semi-static key). If a unique identifier is not used in step 501, the secure element-diversified key K_(SE) may also be generated in step 501 as a function of the master key K_(M) and the password.

The secure element-diversified key K_(SE) is an AES key in various embodiments, and is

After the secure element-diversified key K_(SE) is generated in step 501, host key information HK_(SE) is encrypted using the secure element-diversified key K_(SE) to generate encrypted host key information CHK_(SE) in step 503. The encrypted host key information CHK_(SE) is then stored in secure memory of the secure element in step 504. The host key information HK_(SE) is also stored in a secure element host key information slot (SE-HK_(SE) slot) of the secure element in step 502.

Optionally, if the secure element and the host device are at geographically separate locations, it may be necessary to securely transport the master key K_(M) from a secure element manufacturing location to a host device manufacturing location in step 506. Alternatively, the master key K_(M) may already be at both locations at the initial state 10. In some embodiments, the master key K_(M) could also be securely transported from the host device manufacturing location to the secure element manufacturing location. In applications where a password is used in step 501, the password may also be securely transported from the secure element manufacturing location to the host device manufacturing location in step 506.

The master key K_(M) is obfuscated using a host device unique identifier UID_(HD) to generate a host device-obfuscated key K_(HD) within system operational code (SOC) stored in protected memory of the host device in step 507. The obfuscation may include encryption or any suitable form of obfuscation within the system operational code or physically within the host device. For example, the obfuscation may also include a form of tamper-resistant memory. The host device-obfuscated key K_(HD) may be different from the secure element-diversified key K_(SE) and has similar cryptographic advantages. As before, in some embodiments, the master key K_(M) may be obfuscated without using a unique identifier and a password may or may not be included in the obfuscation process. For example, a password which may be the same as the password optionally used in step 501 may be used in step 507 along with the host device unique identifier UID_(HD) to obfuscate the master key K_(M). The system operational code of the host device is capable of reversing the obfuscation of the host device-obfuscated key K_(HD) to recover the master key K_(M).

After step 504 and step 507 have both been performed, the secure element is cryptographically aligned with the host device in aligned state 520. Specifically, the encrypted host key information CHK_(SE) is stored in the secure element and the host device-obfuscated key K_(HD) is stored in the host device. The aligned state 520 may be a specific description of other aligned states described herein such as the aligned state 120 of FIG. 1, for example.

FIG. 6 illustrates a method of cryptographically binding a secure element to a host device using a master key and encrypted host key information in accordance with an embodiment of the invention. The method of FIG. 6 may be a specific implementation of other methods described herein, such as the cryptographic binding method 200 of FIG. 2, for example. Similarly labeled elements may be as previously described.

Referring to FIG. 6, a cryptographic binding method 600 includes an initial state which is an aligned state 520 in which a secure element and a host device are cryptographically aligned. The alignment may be performed in accordance with cryptographic alignment methods as describe herein, such as the cryptographic alignment method 500 of FIG. 5, for example. The alignment process may be geographically separated from a binding location where the cryptographic binding method 600 is performed and at which the secure element and the host device are collocated. For example, the binding location may be a chipset manufacturing location that is remote to locations such as a secure element manufacturing location and a host device manufacturing location.

After the aligned state 520, the secure element is operationally coupled to the host device in step 210 as previously described. The binding process may optionally be initiated by sending a predetermined command to the host device in step 211 and the secure element may optionally be unlocked by a password in step 212, also as previously described. After step 210, the host device reads encrypted host key information CHK_(SE) and a secure element unique identifier UID_(SE) from the secure element in step 615. If the secure element unique identifier UID_(SE) was not involved in the cryptographic alignment process that resulted in the aligned state 520, then the secure element unique identifier UID_(SE) may optionally not be read by the host device in step 615.

The host device reverses the host device-obfuscated key K_(HD) to generate the master key K_(M) in step 616. The reverse obfuscation process may use a password such as may be provided in step 611 and/or step 612. The reverse obfuscation process may also use a host device unique identifier UID_(HD). The host device decrypts the encrypted host key information CHK_(SE) using the master key K_(M) and the secure element unique identifier UID_(SE) to generate host key information HK_(SE) in step 617. For example, the host device may recreate the secure element diversified key K_(SE) using the master key K_(M) together with the secure element unique identifier UID_(SE) (and a password if a password was used during the cryptographic alignment process that resulted in the aligned state 520).

After the host key information HK_(SE) is generated by the host device in step 617, the host device stores the host key information HK_(SE) in a host device host key information slot (HD-HK_(SE) slot) of the host device in step 618. Once the host key information HK_(SE) is stored in both the HD-HK_(SE) slot of the host device in step 618 and in the SE-HK_(SE) slot of the secure element prior to the aligned state 520, the secure element is cryptographically bound to the host device in bound state 30, which may be as previously described.

FIG. 7 illustrates schematic block diagrams of a secure element, host device, and hardware security modules usable for cryptographic alignment, binding, and secure acquisition of proprietary information using a master key and encrypted host key information in accordance with an embodiment of the invention. The schematic block diagrams of FIG. 7 may schematically illustrate implementations of one or more of the methods described herein, such as the cryptographic alignment method 500, the cryptographic binding method 600, and the method of acquiring proprietary information 300 of FIGS. 5, 6, and 3 respectively, as examples. Further, the schematic block diagrams of FIG. 7 may be specific implementations of other schematic block diagrams described herein, such as the schematic block diagrams of FIG. 4, for example. Similarly labeled elements may be as previously described.

Referring to FIG. 7, the schematic block diagrams include a secure element 750 (SE 750), a secure element hardware security module 770 (HSM_(SE) 770), a host device 760 (HD 760), and a host device hardware security module 780. The secure element 750 may be a specific implementation of the secure element 450 of FIG. 4. In the same way, the host device 760 may be a specific implementation of the host device 460 of FIG. 4.

Similar to other hardware security modules previously described, the HSM_(SE) 770 may optionally be included at the secure element manufacturing location 95 and the HSM_(HD) 780 may optionally be included at the host device manufacturing location 96. The HSM_(SE) 770 and the HSM_(HD) 780 may be specific implementations of the HSM_(SE) 470 and the HSM_(HD) 480 of FIG. 4, respectively.

A secure element-diversified key K_(SE) is generated as a function of a master key K_(M) in step 701. The secure element-diversified key K_(SE) may be generated by the HSM_(SE) 770. A secure element unique identifier UID_(SE) and/or a password such as a batch password may also be used in combination with the master key K_(M) to generate the secure element-diversified key K_(SE). The secure element-diversified key K_(SE) is used to encrypt host key information HK_(SE) to generate encrypted host key information CHK_(SE) in step 703. The encrypted host key information HK_(SE) is stored in secure memory 52 of the secure element 750 in step 704. Optionally, the master key K_(M) is securely transported from the secure element manufacturing location 95 to the host device manufacturing location 96 in step 706.

The host key information HK_(SE) is stored in a secure element host key information slot 56 (SE-HK_(SE) slot 56) of the secure element 750 in step 702. The host key information HK_(SE) may be generated by the HSM_(SE) 770. For example, the host key information HK_(SE) may be securely installed in the SE-HK_(SE) slot 56 of the secure element 750 by the HSM_(SE) 770. A proprietary information key K_(PI) is wrapped to form a wrapped proprietary information key WK_(PI) in step 421. The wrapped proprietary information key WK_(PI) is stored in the secure memory 52 of the secure element 750 in step 422.

Still referring to FIG. 7, the master key K_(M) is obfuscated to generate a host device-obfuscated key K_(HD) and stored in system operational code 764 (SOC 764) of the host device 760 in step 707. For example, the HSM_(HD) 780 may generate the host device-obfuscated key K_(HD). The host device-obfuscated key K_(HD) may be obfuscated using a host device unique identifier UID_(HD) and/or a password such as a batch password. The password may be the same or different from the password that may be used to generate the secure element-diversified key K_(SE) in step 701. Encrypted proprietary information CPI may optionally be stored in protected memory 62 of the host device 1060 in step 441.

The secure element 750 may be cryptographically bound to the host device 760 at a chipset manufacturing location 97 which may be geographically separate from (i.e. remote to) both the secure element manufacturing location 95 and the host device manufacturing location 96. The secure element 750 is transported from the secure element manufacturing location 95 to the chipset manufacturing location 97 in step 708. Similarly, the host device 760 is transported from the host device manufacturing location 96 to the chipset manufacturing location 97 in step 709. At this point, the secure element 750 and the host device 760 are collocated at the chipset manufacturing location 97. That is, the secure element 750 and the host device 760 are physically in the same location.

The secure element 750 is operatively coupled to the host device 760 in step 710. The host device 760 reads the encrypted host key information CHK_(SE) from the secure element 750 in step 715. In step 716, the host device 760 reverses the obfuscation of the host device-obfuscated key K_(HD) to generate the master key K_(M). The host device unique identifier UID_(HD) and/or the password optionally used in step 707 may be used to in step 716 to reverse the obfuscation. The host device 760 then decrypts the encrypted host key information CHK_(SE) using the master key K_(M) and optionally the secure element unique identifier UID_(SE) to generate the host key information HK_(SE) in step 717 and stores the host key information HK_(SE) in the HD-HK_(SE) slot 66 of the host device 760 in step 718. For example, the host device 760 may read the secure element unique identifier UID_(SE) from the secure element 750 in step 715 or at some other time after step 710. The host device 760 may use the master key K_(M) and the secure element unique identifier UID_(SE) to generate the secure element-diversified key K_(SE) internally in order to decrypt the encrypted host key information CHK_(SE).

After the host key information HK_(SE) has been installed in the HD-HK_(SE) slot 66 of the host device 760, the master key K_(M) and the host device-obfuscated key K_(HD) are optionally deleted in step 719 to further protect the anonymity of the host key information HK_(SE). For example the binding process stored in the system operational code 764 may be atomic and delete all key material as soon as it is used. Once the host key information HK_(SE) is stored in both the SE-HK_(SE) slot 56 and the HD-HK_(SE) slot 66, the secure element 750 and the host device 760 are cryptographically bound.

After the secure element 750 and the host device 760 are cryptographically bound, the host device 760 uses the host key information HK_(SE) stored in the HD-HK_(SE) slot 66 to read the wrapped proprietary information key WK_(PI) from the secure element 750 in step 431 and instruct the secure element 750 to unwrap the wrapped proprietary information key WK_(PI) to generate the proprietary information key K_(PI) in step 432. The proprietary information key K_(PI) is then provided to the host device 760 in step 433. In step 434, the host device 760 uses the proprietary information key K_(PI) to decrypt the encrypted proprietary information CPI and generate the proprietary information PI.

As previously noted, the methods and schematic diagrams of FIGS. 5-7 may be specific implementations of the methods and schematic diagrams of FIGS. 1-4. For example, the encrypted host key information CHK_(SE) may be a specific implementation of the binding information B_(SE). Additionally, the secure element-diversified key K_(SE) and the host device-obfuscated key K_(HD) may be specific implementations of the first secret key SK₁ and the second secret key SK₂ respectively.

FIG. 8 illustrates a method of cryptographically aligning a secure element with a host device using a secure element public key and a host device private key in accordance with an embodiment of the invention. The method of FIG. 8 may be a specific implementation of other methods described herein, such as the cryptographic alignment method 100 of FIG. 1, for example. Similarly labeled elements may be as previously described.

Referring to FIG. 8, a cryptographic alignment method 800 includes the initial state 10 which may be as previously described. A secure element private key n_(SE) is generated in step 801. The secure element private key n_(SE) may be an ECC private key that is part of an ECDH key pair in some embodiments. For example, the ECDH key pair may be generated using a preselected set of parameters. The set of parameters may define a prime curve or a binary curve. For example, a prime curve may be over the set of integers {0, 1, . . . p−1} where p is a prime number (i.e. Z_(p)). As another example, a binary curve may be over the Galois field GF(2^(m)) where m is a positive integer. The preselected set of parameters may conform to a set of recognized standards such as National Institute of Standards and Technology (NIST) recommended curve or an ECC Brainpool standard curve.

The secure element private key n_(SE) may be generated by the secure element or an external entity such as a hardware security module. The secure element private key n_(SE) may be diversified from a master key in one embodiment. For example, the secure element private key n_(SE) may be derived from some combination of a secure element master key, a secure element unique identifier, and a password such as a batch password. The secure element private key n_(SE) may be used to create a secure element public key P_(SE) in step 803. The secure element public key P_(SE) may be an ECC public key of the ECDH key pair, for example. The secure element public key P_(SE) may then be stored in secure memory of the secure element in step 804. Alternatively, creation of the secure element public key P_(SE) may be deferred to a later time and the secure element private key n_(SE) may be stored in secure memory of a secure element in step 805.

A host device private key n_(HD) is stored within system operational code stored in protected memory of the host device in step 807. The host device private key n_(HD) may be an ECC private key that is part of an ECDH key pair and generated according to the same ECC parameters used to generate the (n_(SE), P_(SE)) ECDH key pair. The host device private key n_(HD) may be diversified similar to the secure element private key n_(SE) with a host device master key, a host device unique identifier, and a password such as batch password. It should be noted that it may be considered advantageous from a security perspective for the host device private key n_(HD) and the secure element private key n_(SE) to be diversified using separate keys rather than a single master key as in some previously described embodiments. For example, if used, the secure element master key and the host device master key may not be cryptographically correlated.

After the host device private key n_(HD) is stored in the host device in step 807 and either the secure element private key n_(SE) is stored in the secure element in step 805 or the secure element public key P_(SE) is stored in the secure element in step 804, the secure element is cryptographically aligned with the host device in an aligned state 820. The aligned state 820 may be a specific description of other aligned states described herein such as the aligned state 120 of FIG. 1, for example.

A host device public key P_(HD) may optionally be created from the host device private key n_(HD) prior to the aligned state 820. The host device public key P_(HD) may be an ECC public key of the (n_(HD), P_(HD)) ECDH key pair, for example. In some embodiments, the host device private key n_(HD) and the host device public key P_(HD) may be a static key pair that is reused for more than one host device. That is, in this specific scenario, both the host device private key n_(HD) and the host device public key P_(HD) may be kept secret and the host device public key P_(HD) may be public only in the sense that it is made known to the secure element. Optionally, the host device public key P_(HD) is securely transported from a host device manufacturing location to a secure element manufacturing location in step 806. Also prior to the aligned state 820, host key information HK_(SE) may be stored in a secure element host key slot (SE-HK_(SE) slot) of the secure element in step 802. The host key information may be generated using the secure element private key n_(SE) and the host device public key P_(HD).

It should also be noted that, prior to the aligned state 820, signed certificates may be installed in the secure element and/or the host device. For example, an HSM_(SE) may create a secure element certificate C_(SE) using a certificate authority (CA) signing-private-key and install the secure element certificate C_(SE) in the secure element prior to the aligned state 820. Additionally or alternatively, an HSM_(HD) may create a host device certificate C_(HD) using a CA signing-private-key and install the host device certificate C_(HD) in the host device prior to the aligned state 820. These certificates may be used, for example, during the binding process to allow the host device to verify it is pairing with an authorized secure element, and for the secure element to verify it is being paired with an authorized host device.

FIG. 9 illustrates a method of cryptographically binding a secure element to a host device using a secure element public key and a host device private key in accordance with an embodiment of the invention. The method of FIG. 9 may be a specific implementation of other methods described herein, such as the cryptographic binding method 200 of FIG. 2, for example. Similarly labeled elements may be as previously described.

Referring to FIG. 9, a cryptographic binding method 900 includes an initial state which is an aligned state 820 in which a secure element and a host device are cryptographically aligned. The alignment may be performed in accordance with cryptographic alignment methods as describe herein, such as the cryptographic alignment method 800 of FIG. 8, for example. The alignment process may be geographically separated from a binding location where the cryptographic binding method 900 is performed and at which the secure element and the host device are collocated. For example, the binding location may be a chipset manufacturing location that is remote to locations such as a secure element manufacturing location and a host device manufacturing location.

After the aligned state 820, the secure element is operationally coupled to the host device in step 210 as previously described. The binding process may optionally be initiated by sending a predetermined command to the host device in step 211 and the secure element may optionally be unlocked by a password in step 212, also as previously described. After step 210, a secure element public key P_(SE) is optionally created using a secure element private key n_(SE) in step 903 if it has not already been created prior to the aligned state 820. For example, the secure element may create the secure element public key P_(SE) internally. After the secure element contains the secure element public key P_(SE), the host device reads the secure element public key P_(SE) from the secure element in step 915.

The host device creates host key information HK_(SE) using a host device private key n_(HD) and the secure element public key P_(SE) in step 917. After the host key information HK_(SE) is generated by the host device in step 917, the host device stores the host key information HK_(SE) in a host device host key information slot (HD-HK_(SE) slot) of the host device in step 918. If the host key information HK_(SE) is not stored in the secure element prior to the aligned state 820, the host key information HK_(SE) is optionally created using the secure element private key n_(SE) and a host device public key P_(HD) in step 913. Similar to step 917, the host device public key P_(HD) may be created by the host device using the host device private key n_(HD). The host device public key P_(HD) may be sent to the secure element by the host device as part of the binding process after step 210, but before step 913.

After the host key information is created by the secure element in step 913, the host key information HK_(SE) is stored in a secure element host key information slot (SE-HK_(SE) slot) of the secure element in step 914. Once the host key information HK_(SE) is stored in both the HD-HK_(SE) slot of the host device in step 918 and in the SE-HK_(SE) slot of the secure element either prior to the aligned state 820 or in step 914, the secure element is cryptographically bound to the host device in bound state 30, which may be as previously described.

In some embodiments, signed certificates may be used during the binding process to verify that the public keys sent between the host device and the secure element are valid. For example, a secure element certificate C_(SE) may be signed by an HSM_(SE) and stored in the secure element prior to the aligned state 820. Then, the host device may verify that the secure element public key P_(SE) is valid (i.e. sent by a legitimate secure element) in step 915 by verifying the secure element certificate C_(SE) using a certificate authority (CA) public key that corresponds to the secure element (e.g. the CA signing-private-key used be the HSM_(SE) to create the secure element certificate C_(SE)). Similarly, in embodiments where the secure element creates the host key information HK_(SE) after the aligned state 820 (e.g. in step 913) a host device certificate C_(HD) may be signed by an HSM_(HD) and stored in the host device prior to the aligned state 820. The secure element may then verify that the host device public key P_(HD) is valid (i.e. sent by a legitimate host device) in step 913 by verifying the host device certificate C_(HD) using a CA public key that corresponds to the host device (e.g. the CA signing-private-key used be the HSM_(HD) to create the host device certificate C_(HD)). In other words, signed certificates may be used by the host device and/or the secure element to verify that the device with which it is engaging is authorized to be bound to it.

FIG. 10 illustrates schematic block diagrams of a secure element, host device, and hardware security modules usable for cryptographic alignment, binding, and secure acquisition of proprietary information using a secure element public key and a host device private key in accordance with an embodiment of the invention. The schematic block diagrams of FIG. 10 may schematically illustrate implementations of one or more of the methods described herein, such as the cryptographic alignment method 700, the cryptographic binding method 800, and the method of acquiring proprietary information 300 of FIGS. 7, 8, and 3 respectively, as examples. Further, the schematic block diagrams of FIG. 10 may be a specific implementation of other schematic block diagrams described herein, such as the schematic block diagrams of FIG. 4, for example. Similarly labeled elements may be as previously described.

Referring to FIG. 10, the schematic block diagrams include a secure element 1050 (SE 1050), a secure element hardware security module 1070 (HSM_(SE) 1070), a host device 1060 (HD 1060), and a host device hardware security module 1080. The secure element 1050 may be a specific implementation of the secure element 450 of FIG. 4. In the same way, the host device 1060 may be a specific implementation of the host device 460 of FIG. 4.

Similar to other hardware security modules previously described, the HSM_(SE) 1070 may optionally be included at the secure element manufacturing location 95 and the HSM_(HD) 1080 may optionally be included at the host device manufacturing location 96. The HSM_(SE) 1070 and the HSM_(HD) 1080 may be specific implementations of the HSM_(SE) 470 and the HSM_(HD) 480 of FIG. 4, respectively.

A secure element private key n_(SE) is generated in step 1001. The secure element private key n_(SE) is either stored in secure memory 52 of the secure element 1050 in step 1005 or used to generate a secure element public key P_(SE) in step 1003. If the secure element public key P_(SE) is generated in step 1003, the secure element public key P_(SE) is then stored in the secure memory 52 of the secure element 1050 in step 1004. Alternatively, after the secure element private key n_(SE) is stored in the secure memory 52 in step 1005, the secure element 1050 may create the secure element public key P_(SE) internally in step 1003 and then store the secure element public key P_(SE) in the secure memory 52 in step 1004.

Optionally, a host device public key P_(HD) may be used in combination with the secure element private key n_(SE) to generate host key information HK_(SE) in step 1013. If the host device public key P_(HD) is not already located at the secure element manufacturing location 95 (e.g. in the HSM_(SE) 1070) then host device public key P_(HD) may be securely transported from a host device manufacturing location 96 to the secure element manufacturing location 95 in step 1006. The host key information HK_(SE) may be generated by the HSM_(SE) 1070. Then, the host key information HK_(SE) may be optionally be stored in a secure element host key information slot 56 (SE-HK_(SE) slot 56) of the secure element 1050 in step 1002. For example, the host key information HK_(SE) may be securely installed in the SE-HK_(SE) slot 56 of the secure element 1050 by the HSM_(SE) 1070. A proprietary information key K_(PI) is wrapped to form a wrapped proprietary information key WK_(PI) in step 421. The wrapped proprietary information key WK_(PI) is stored in the secure memory 52 of the secure element 1050 in step 422.

Still referring to FIG. 10, a host device private key n_(HD) is stored in system operational code 1064 (SOC 1064) of the host device 1060 in step 1007. For example, the HSM_(HD) 1080 may generate the host device private key n_(HD). Alternatively, the host device private key n_(HD) may be a static key known only to the HSM_(HD) 1080. The host device public key P_(HD) is optionally created using the host device private key n_(HD) in step 1023 prior to step 1006. Encrypted proprietary information CPI may optionally be stored in protected memory 62 of the host device 1060 in step 441.

The secure element 1050 may be cryptographically bound to the host device 1060 at a chipset manufacturing location 97 which may be geographically separate from (i.e. remote to) both the secure element manufacturing location 95 and the host device manufacturing location 96. The secure element 1050 is transported from the secure element manufacturing location 95 to the chipset manufacturing location 97 in step 1008. Similarly, the host device 1060 is transported from the host device manufacturing location 96 to the chipset manufacturing location 97 in step 1009. At this point, the secure element 1050 and the host device 1060 are collocated at the chipset manufacturing location 97. That is, the secure element 1050 and the host device 1060 are physically in the same location.

The secure element 1050 is operatively coupled to the host device 1060 in step 1010. If the secure element 1050 does not have a secure element public key P_(SE) prior to step 1010, the secure element 1050 creates the secure element public key P_(SE) using the secure element private key n_(SE) in step 1003. The host device 1060 reads the secure element public key P_(SE) from the secure element 1050 in step 1015. The host device 1060 generates host key information HK_(SE) using the host device private key n_(HD) and the secure element public key P_(SE) in step 1017 and stores the host key information HK_(SE) in the HD-HK_(SE) slot 66 of the host device 1060 in step 1018. After the host key information HK_(SE) has been installed in the HD-HK_(SE) slot 66 of the host device 1060, the host device private key n_(HD) and the secure element public key P_(SE) are optionally deleted in step 1019 to further protect the anonymity of the host key information HK_(SE). For example the binding process stored in the system operational code 1064 may be atomic and delete all key material as soon as it is used.

If the host key information HK_(SE) was not stored in the secure element 1050 prior to step 1010, the secure element 1050 may create the host key information using the secure element private key n_(SE) and the host device public key P_(HD) in step 1013 and store the host key information HK_(SE) in the SE-HK_(SE) slot 56 of the secure element 1050 in step 1014. The host device 1060 may create the host device public key P_(HD) internally using the host device private key n_(HD) in step 1035. The host device 1060 may send the host device public key P_(HD) to the secure element 1050 in step 1036 at some time after step 1010.

Once the host key information HK_(SE) is stored in both the SE-HK_(SE) slot 56 and the HD-HK_(SE) slot 66, the secure element 1050 and the host device 1060 are cryptographically bound. The host device 1060 uses the host key information HK_(SE) stored in the HD-HK_(SE) slot 66 to read the wrapped proprietary information key WK_(PI) from the secure element 1050 in step 431 and instruct the secure element 1050 to unwrap the wrapped proprietary information key WK_(PI) to generate the proprietary information key K_(PI) in step 432. The proprietary information key K_(PI) is then provided to the host device 1060 in step 433. In step 434, the host device 1060 uses the proprietary information key K_(PI) to decrypt the encrypted proprietary information CPI and generate the proprietary information PI.

As previously noted, the methods and schematic diagrams of FIGS. 8-10 may be specific implementations of the methods and schematic diagrams of FIGS. 1-4. For example, the secure element public key P_(SE) may be a specific implementation of the binding information B_(SE). Additionally, the secure element private key n_(SE) and the host device private key n_(HD) may be specific implementations of the first secret key SK₁ and the second secret key SK₂ respectively.

Example embodiments of the invention are summarized here. Other embodiments can also be understood from the entirety of the specification as well as the claims filed herein.

Example 1

A method of cryptographically binding a secure element to a host device (HD), the method including: storing host key information HK_(SE) in an SE-HK_(SE) slot of the secure element; at a first location, storing binding information B_(SE) in secure memory of the secure element, where the binding information B_(SE) is cryptographically correlated with the host key information HK_(SE); at a second location remote to the first location, storing a second secret key SK₂ within system operational code stored in protected memory of the host device, where the second secret key SK₂ is cryptographically correlated with the host key information KH_(SE); and at a third location, after storing the binding information B_(SE), and after storing the second secret key SK₂, operationally coupling the secure element to the host device, reading, by the host device, the binding information B_(SE) from the secure element, generating, by the host device, the host key information HK_(SE) using the binding information B_(SE) and the second secret key SK₂, and storing, by the host device, the host key information HK_(SE) in an HD-HK_(SE) slot of the host device, where the secure element and the host device are collocated at the third location, and where the third location is remote to both the first location and the second location.

Example 2

The method of example 1, where: operationally coupling the secure element to the host device includes electrically coupling the secure element to the host device using a data bus; and reading the binding information B_(SE) from the secure element includes transmitting the binding information B_(SE) from the secure element to the host device through the data bus.

Example 3

The method of one of examples 1 and 2, further including: deleting, by the host device, the second secret key SK₂ after storing the host key information HK_(SE) in the HD-HK_(SE) slot.

Example 4

The method of one of examples 1 to 3, where: the binding information B_(SE) includes encrypted host key information CKH_(SE); the encrypted host key information CHK_(SE) is encrypted using a symmetric-key cryptographic algorithm; and storing the host key information HK_(SE) in the SE-HK_(SE) slot of the secure element includes storing the host key information HK_(SE) in the secure element at the first location.

Example 5

The method of one of examples 1 to 3, where: the binding information B_(SE) is a secure element public key P_(SE); the second secret key SK₂ is a host device private key n_(HD); and generating the host key information HK_(SE) includes creating, by the host device, the host key information HK_(SE) using the secure element public key P_(SE) and the host device private key n_(HD).

Example 6

The method of one of examples 1 to 3, further including: at the first location, storing the first secret key SK₁ in the secure memory of the secure element, where the first secret key SK₁ is a secure element private key n_(SE); at the third location and after operationally coupling the secure element to the host device sending, by the host device, a host device public key P_(HD) to the secure element, and creating, by the secure element, the host key information HK_(SE) using the host device public key P_(HD) and the secure element private key n_(SE); and where storing the host key information HK_(SE) in the SE-HK_(SE) slot of the secure element includes storing the host key information HK_(SE) at the third location after creating the host key information HK_(SE) using the host device public key P_(HD) and the secure element private key n_(SE).

Example 7

The method of one of examples 1 to 6, further including: generating, by a first hardware security module HSM_(SE) at the first location, the first secret key SK₁; generating, by a second hardware security module HSM_(HD) at the second location, the second secret key SK₂; and where steps performed at the third location are performed without using a hardware security module.

Example 8

The method of one of examples 1 to 7, further including: storing a secure-backup-data file in secure memory of the secure element, where the secure-backup-data file includes encrypted host key backup information usable to recover host devices for which the host key information HK_(SE) stored in the HD-HK_(SE) slot of the host device has become corrupted.

Example 9

The method of one of examples 1 to 8, further including: at the third location after operationally coupling the secure element and the host device and before reading the binding information B_(SE), unlocking the secure element using a batch password.

Example 10

The method of one of examples 1 to 9, further including: at the first location after storing the host key information HK_(SE) in the SE-HK_(SE) slot of the secure element and before operationally coupling the secure element to the host device, wrapping a proprietary information key K_(PI) to form a wrapped proprietary information key WK_(PI), and storing the wrapped proprietary information key WK_(PI) in the secure memory of the secure element; loading encrypted proprietary information into the host device; and at the third location after storing the host key information HK_(SE) in the HD-HK_(SE) slot of the host device, reading the wrapped proprietary information key WK_(PI) from the secure element, instructing, by the host device using the host key information HK_(SE) stored in the HD-HK_(SE) slot of the host device, the secure element to unwrap the wrapped proprietary information key WK_(PI) and provide the proprietary information key K_(PI) to the host device, and decrypting the encrypted proprietary information using the proprietary information key K_(PI).

Example 11

The method of one of examples 1 to 10, further including: at the first location and before operationally coupling the secure element to the host device, preinstalling a wrapped license key K₁ into the secure memory of the secure element, the wrapped license key K₁ corresponding to proprietary executable computer code; and at the third location and after storing the host key information HK_(SE) in the HD-HK_(SE) slot of the host device, using, by the host device, the secure element as a hardware license to verify permission to install the proprietary executable computer code by unwrapping the wrapped license key K₁ using the host key information HK_(SE), and installing, by the host device, the proprietary executable computer code in the host device.

Example 12

The method of example 11, where the proprietary executable computer code is proprietary firmware.

Example 13

The method of example 11, further including: after using the secure element as the hardware license, decrementing a counter of the secure element, where the counter tracks a quantity of installations of the proprietary executable computer code, and where the secure element is configured to disallow installation of the proprietary executable computer code when the counter is equal to zero.

Example 14

A method of cryptographically aligning a secure element with a host device, the method including: generating a secure element-diversified key K_(SE) as a function of a master key K_(M) and a secure element unique identifier UID_(SE); encrypting host key information HK_(SE) using the secure element-diversified key K_(SE) to generate encrypted host key information CHK_(SE), where the host key information HK_(SE) uniquely corresponds to the secure element; storing the host key information HK_(SE) in a SE-HK_(SE) slot of the secure element; storing the encrypted host key information CHK_(SE) in secure memory of the secure element; and obfuscating the master key K_(M) using a host device unique identifier UID_(HD) to generate a host device-obfuscated key K_(HD) within system operational code stored in protected memory of the host device.

Example 15

The method of example 14, where the host key information HK_(SE) includes a host message authentication code (MAC) key and a host cipher key.

Example 16

The method of one of examples 14 and 15, where the secure element-diversified key K_(SE) is an advanced encryption standard (AES) key.

Example 17

The method of one of examples 14 to 16, where: generating the secure element-diversified key K_(SE) further includes generating the secure element-diversified key K_(SE) as a function of the master key K_(M), the secure element unique identifier UID_(SE), and a batch password; and obfuscating the master key K_(M) further includes obfuscating the master key K_(M) using the host device unique identifier UID_(HD) and the batch password.

Example 18

The method of one of examples 14 to 17, further including: operationally coupling the secure element to the host device; and executing the system operational code by the host device, where executing the system operational code includes reading the encrypted host key information CHK_(SE) and the secure element unique identifier UID_(SE) from the secure element, reversing obfuscation of the host device-obfuscated key K_(HD) to generate the master key K_(M), decrypting the encrypted host key information CHK_(SE) using the master key K_(M) and the secure element unique identifier UID_(SE) to generate the host key information HK_(SE), and storing the host key information HK_(SE) in an HD-HK_(SE) slot of the host device.

Example 19

The method of example 18, further including: after storing the host key information HK_(SE) in the HD-HK_(SE) slot of the secure element and before executing the system operational code, instructing the secure element to wrap a proprietary information key K_(PI) to form a wrapped proprietary information key WK_(PI), and store the wrapped proprietary information key WK_(PI) in the secure memory of the secure element; sending encrypted proprietary information to the host device; and where executing the system operational code further includes reading the wrapped proprietary information key WK_(PI) from the secure element, using the host key information HK_(SE) stored in the HD-HK_(SE) slot of the host device, instructing the secure element to unwrap the wrapped proprietary information key WK_(PI) and provide the proprietary information key K_(PI) to the host device, and decrypting the encrypted proprietary information using the proprietary information key K_(PI).

Example 20

The method of example 19, where the encrypted proprietary information includes firmware to be installed on the host device.

Example 21

The method of one of examples 18 and 19, further including: before executing the system operational code, sending an initiate command to the host device triggering boot-up of the system operational code, where the initiate command includes a batch password; and where executing the system operational code further includes unlocking the secure element using the batch password.

Example 22

The method of one of examples 18 to 21, further including: after storing the host key information HK_(SE) in the HD-HK_(SE) slot of the host device, deleting the master key K_(M) and the host device-obfuscated key K_(HD) from the host device.

Example 23

A method of cryptographically binding a secure element to a host device, the method including: storing a secure element private key n_(SE) in secure memory of the secure element; creating a secure element public key P_(SE) using the secure element private key n_(SE); storing a host device private key n_(HD) within system operational code stored in protected memory of the host device; operationally coupling the secure element and the host device; and executing the system operational code by the host device, where executing the system operational code includes reading the secure element public key P_(SE) from the secure element, creating host key information HK_(SE) using the host device private key n_(HD) and the secure element public key P_(SE), and storing the host key information HK_(SE) in a HD-HK_(SE) slot of the host device.

Example 24

The method of example 23, further including: before operationally coupling the secure element to the host device, creating a host device public key P_(HD) using the host device private key n_(HD), creating the host key information HK_(SE) using the secure element private key n_(SE) and the host device private key n_(HD), and storing the host key information HK_(SE) in a SE-HK_(SE) slot of the secure element.

Example 25

The method of example 24, where creating the host device public key P_(HD) and creating the host key information HK_(SE) using the secure element private key n_(SE) and the host device private key n_(HD) are performed by a hardware security module HSM_(SE).

Example 26

The method of one of examples 23 to 25, further including: where executing the system operational code further includes creating a host device public key P_(HD) using the host device private key n_(HD), and sending the host device public key P_(HD) to the secure element; creating, by the secure element, the host key information HK_(SE) using the secure element private key n_(SE) and the host device public key P_(HD); and storing, by the secure element, the host key information HK_(SE) in a SE-HK_(SE) slot of the secure element.

Example 27

The method of one of examples 23 to 26, further including: after storing the host key information HK_(SE) in the HD-HK_(SE) slot of the host device, deleting the host device private key n_(HD) from the host device.

Example 28

The method of one of examples 23 to 27, where: the secure element private key n_(SE) and the secure element public key P_(SE) are a first elliptic-curve Diffie-Hellman (ECDH) key pair generated according to a predetermined set of elliptic-curve cryptography (ECC) parameters.

Example 29

The method of example 28, further including: creating a host device public key P_(HD) using the host device private key n_(HD), where the host device private key n_(HD) and the host device public key P_(HD) are a second ECDH key pair generated according to the predetermined set of ECC parameters; creating, by the secure element, the host key information HK_(SE) using the secure element private key n_(SE) and the host device public key P_(HD); and storing, by the secure element, the host key information HK_(SE) in a SE-HK_(SE) slot of the secure element.

Example 30

The method of example 28, where the predetermined set of ECC parameters defines a prime curve over Z_(p).

Example 31

The method of example 28, where the predetermined set of ECC parameters defines a binary curve over GF(2^(m)).

Example 32

The method of one of examples 23 to 31, further including: generating, by a secure element hardware security module, a secure element certificate; storing the secure element certificate in the secure element; generating, by a host device hardware security module, a host device certificate; storing the host device certificate in the host device; and after operationally coupling the secure element and the host device, verifying, by the host device, that the secure element is authorized to pair with the host device by validating the secure element certificate using a secure element public key, and verifying, by the secure element, that the host device is authorized to pair with the secure element by validating the host device certificate using a host device public key.

Example 33

The method of one of examples 23 to 32, further including: generating the secure element private key n_(SE) as a function of a secure element unique identifier UID_(SE).

Example 34

The method of one of examples 23 to 33, further including: generating the host device private key n_(HD) as a function of a host device unique identifier UID_(HD).

Example 35

The method of one of examples 23 to 34, further including: before executing the system operational code, sending an initiate command to the host device triggering boot-up of the system operational code, where the initiate command includes a batch password; and where executing the system operational code further includes unlocking the secure element using the batch password.

While this invention has been described with reference to illustrative embodiments, this description is not intended to be construed in a limiting sense. Various modifications and combinations of the illustrative embodiments, as well as other embodiments of the invention, will be apparent to persons skilled in the art upon reference to the description. For example, one or more of the embodiments of FIGS. 1-10 may be combined in further embodiments. It is therefore intended that the appended claims encompass any such modifications or embodiments. 

What is claimed is:
 1. A method of cryptographically binding a secure element (SE) to a host device (HD), the method comprising: storing host key information HK_(SE) in an SE-HK_(SE) slot of the secure element; at a first location, storing binding information B_(SE) in secure memory of the secure element, wherein the binding information B_(SE) is cryptographically correlated with the host key information HK_(SE); at a second location remote to the first location, storing a second secret key SK₂ within system operational code stored in protected memory of the host device, wherein the second secret key SK₂ is cryptographically correlated with the host key information HK_(SE); and at a third location, after storing the binding information B_(SE), and after storing the second secret key SK₂, cryptographically binding the secure element to the host device by operationally coupling the secure element to the host device, reading, by the host device, the binding information B_(SE) from the secure element, generating, by the host device, the host key information HK_(SE) using the binding information B_(SE) and the second secret key SK₂, and storing, by the host device, the host key information HK_(SE) in an HD-HK_(SE) slot of the host device, wherein the secure element and the host device are collocated at the third location, and wherein the third location is remote to both the first location and the second location.
 2. The method of claim 1, wherein: the binding information B_(SE) comprises encrypted host key information CHK_(SE); the encrypted host key information CHK_(SE) is encrypted using a symmetric-key cryptographic algorithm; and storing the host key information HK_(SE) in the SE-HK_(SE) slot of the secure element comprises storing the host key information HK_(SE) in the secure element at the first location.
 3. The method of claim 1, wherein: the binding information B_(SE) is a secure element public key P_(SE); the second secret key SK₂ is a host device private key n_(HD); and generating the host key information HK_(SE) comprises creating, by the host device, the host key information HK_(SE) using the secure element public key P_(SE) and the host device private key n_(HD).
 4. The method of claim 1, further comprising: at the first location, storing a first secret key SK₁ in the secure memory of the secure element, wherein the first secret key SK₁ is a secure element private key n_(SE); at the third location and after operationally coupling the secure element to the host device sending, by the host device, a host device public key P_(HD) to the secure element, and creating, by the secure element, the host key information HK_(SE) using the host device public key P_(HD) and the secure element private key n_(SE); and wherein storing the host key information HK_(SE) in the SE-HK_(SE) slot of the secure element comprises storing the host key information HK_(SE) at the third location after creating the host key information HK_(SE) using the host device public key P_(HD) and the secure element private key n_(SE).
 5. The method of claim 1, further comprising: generating, by a first hardware security module HSM_(SE) at the first location, a first secret key SK₁; generating, by a second hardware security module HSM_(HD) at the second location, the second secret key SK₂; and wherein steps performed at the third location are performed without using a hardware security module.
 6. The method of claim 1, further comprising: storing a secure-backup-data file in secure memory of the secure element, wherein the secure-backup-data file comprises encrypted host key backup information usable to recover host devices for which the host key information HK_(SE) stored in the HD-HK_(SE) slot of the host device has become corrupted.
 7. The method of claim 1, further comprising: at the first location and before operationally coupling the secure element to the host device, preinstalling a wrapped license key K₁ into the secure memory of the secure element, the wrapped license key K₁ corresponding to proprietary executable computer code; and at the third location and after storing the host key information HK_(SE) in the HD-HK_(SE) slot of the host device, using, by the host device, the secure element as a hardware license to verify permission to install the proprietary executable computer code by unwrapping the wrapped license key K₁ using the host key information HK_(SE), and installing, by the host device, the proprietary executable computer code in the host device.
 8. The method of claim 7, further comprising: after using the secure element as the hardware license, decrementing a counter of the secure element, wherein the counter tracks a quantity of installations of the proprietary executable computer code, and wherein the secure element is configured to disallow installation of the proprietary executable computer code when the counter is equal to zero.
 9. A method of cryptographically aligning a secure element (SE) with a host device (HD), the method comprising: generating a secure element-diversified key K_(SE) as a function of a master key K_(M) and a secure element unique identifier UID_(SE); encrypting host key information HK_(SE) using the secure element-diversified key K_(SE) to generate encrypted host key information CHK_(SE), wherein the host key information HK_(SE) uniquely corresponds to the secure element; storing the host key information HK_(SE) in a SE-HK_(SE) slot of the secure element; storing the encrypted host key information CHK_(SE) in secure memory of the secure element; and obfuscating the master key K_(M) using a host device unique identifier UID_(HD) to generate a host device-obfuscated key KHD within system operational code stored in protected memory of the host device.
 10. The method of claim 9, wherein: generating the secure element-diversified key K_(SE) further comprises generating the secure element-diversified key K_(SE) as a function of the master key K_(M), the secure element unique identifier UID_(SE), and a batch password; and obfuscating the master key K_(M) further comprises obfuscating the master key K_(M) using the host device unique identifier UID_(HD) and the batch password.
 11. The method of claim 9, further comprising: operationally coupling the secure element to the host device; and executing the system operational code by the host device, wherein executing the system operational code comprises reading the encrypted host key information CHK_(SE) and the secure element unique identifier UID_(SE) from the secure element, reversing obfuscation of the host device-obfuscated key K_(HD) to generate the master key K_(M), decrypting the encrypted host key information CHK_(SE) using the master key K_(M) and the secure element unique identifier UID_(SE) to generate the host key information HK_(SE), and storing the host key information HK_(SE) in an HD-HK_(SE) slot of the host device.
 12. The method of claim 11, further comprising: after storing the host key information HK_(SE) in the HD-HK_(SE) slot of the secure element and before executing the system operational code, instructing the secure element to wrap a proprietary information key Kin to form a wrapped proprietary information key WK_(PI), and store the wrapped proprietary information key WK_(PI) in the secure memory of the secure element; sending encrypted proprietary information to the host device; and wherein executing the system operational code further comprises reading the wrapped proprietary information key WK_(PI) from the secure element, using the host key information HK_(SE) stored in the HD-HK_(SE) slot of the host device, instructing the secure element to unwrap the wrapped proprietary information key WK_(PI) and provide the proprietary information key Kin to the host device, and decrypting the encrypted proprietary information using the proprietary information key K_(PI).
 13. The method of claim 11, further comprising: before executing the system operational code, sending an initiate command to the host device triggering boot-up of the system operational code, wherein the initiate command includes a batch password; and wherein executing the system operational code further comprises unlocking the secure element using the batch password.
 14. The method of claim 11, further comprising: after storing the host key information HK_(SE) in the HD-HK_(SE) slot of the host device, deleting the master key K_(M) and the host device-obfuscated key K_(HD) from the host device.
 15. A method of cryptographically binding a secure element (SE) to a host device (HD), the method comprising: storing a secure element private key n_(SE) in secure memory of the secure element; creating a secure element public key P_(SE) using the secure element private key n_(SE); storing a host device private key n_(HD) within system operational code stored in protected memory of the host device; operationally coupling the secure element and the host device; and cryptographically binding the secure element to the host device by executing the system operational code by the host device, wherein executing the system operational code comprises reading the secure element public key P_(SE) from the secure element, creating host key information HK_(SE) using the host device private key n_(HD) and the secure element public key P_(SE), and storing the host key information HK_(SE) in a HD-HK_(SE) slot of the host device.
 16. The method of claim 15, further comprising: before operationally coupling the secure element to the host device, creating a host device public key P_(HD) using the host device private key n_(HD), creating the host key information HK_(SE) using the secure element private key n_(SE) and the host device private key n_(HD), and storing the host key information HK_(SE) in a SE-HK_(SE) slot of the secure element.
 17. The method of claim 15, further comprising: wherein executing the system operational code further comprises creating a host device public key P_(HD) using the host device private key n_(HD), and sending the host device public key P_(HD) to the secure element; creating, by the secure element, the host key information HK_(SE) using the secure element private key n_(SE) and the host device public key P_(HD); and storing, by the secure element, the host key information HK_(SE) in a SE-HK_(SE) slot of the secure element.
 18. The method of claim 15, further comprising: after storing the host key information HK_(SE) in the HD-HK_(SE) slot of the host device, deleting the host device private key n_(HD) from the host device.
 19. The method of claim 15, further comprising: generating, by a secure element hardware security module, a secure element certificate; storing the secure element certificate in the secure element; generating, by a host device hardware security module, a host device certificate; storing the host device certificate in the host device; and after operationally coupling the secure element and the host device, verifying, by the host device, that the secure element is authorized to pair with the host device by validating the secure element certificate using a secure element public key, and verifying, by the secure element, that the host device is authorized to pair with the secure element by validating the host device certificate using a host device public key.
 20. The method of claim 15, further comprising: before executing the system operational code, sending an initiate command to the host device triggering boot-up of the system operational code, wherein the initiate command includes a batch password; and wherein executing the system operational code further comprises unlocking the secure element using the batch password. 